Field of the Invention
The technology disclosed relates to lab based over-the-air (OTA) testing of multiple antenna devices, and more particularly to techniques for OTA testing suitable for producing a test signal to emulate a wireless channel.
Description of Related Art
When designing over-the air testing approaches, channel modeling concepts are applied in order to ensure that the received signal is representative of the desired test condition. The following standard MIMO (multiple-input multiple-output) radio channel model H is defined in ITU-R M.2135 (International Telecommunication Union, Radio Communication Sector, Mobile Series).
                                          H                          u              ,              s              ,              n                                ⁡                      (                          t              ;              τ                        )                          =                ⁢                              ∑                          m              =              1                        M                    ⁢                                          ⁢                                                                      [                                                                                                                                          F                                                          rx                              ,                              u                              ,                              V                                                                                ⁡                                                      (                                                          φ                                                              n                                ,                                m                                                                                      )                                                                                                                                                                                                                    F                                                          rx                              ,                              u                              ,                              H                                                                                ⁡                                                      (                                                          φ                                                              n                                ,                                m                                                                                      )                                                                                                                                ]                                T                            ⁡                              [                                                                                                    α                                                  n                          ,                          m                          ,                          VV                                                                                                                                    α                                                  n                          ,                          m                          ,                          VH                                                                                                                                                                        α                                                  n                          ,                          m                          ,                          HV                                                                                                                                    α                                                  n                          ,                          m                          ,                          HH                                                                                                                    ]                                      ⁡                          [                                                                                                                  F                                                  tx                          ,                          s                          ,                          V                                                                    ⁡                                              (                                                  ϕ                                                      n                            ,                            m                                                                          )                                                                                                                                                                                F                                                  tx                          ,                          s                          ,                          H                                                                    ⁡                                              (                                                  ϕ                                                      n                            ,                            m                                                                          )                                                                                                        ]                                                                      ⁢                  ×                      exp            ⁡                          (                              j                ⁢                                                                  ⁢                2                ⁢                                                      πλ                    0                                          -                      1                                                        ⁡                                      (                                                                                            φ                          _                                                                          n                          ,                          m                                                                    ·                                                                        r                          _                                                                          rx                          ,                          u                                                                                      )                                                              )                                ⁢                      exp            ⁡                          (                              j                ⁢                                                                  ⁢                2                ⁢                                                      πλ                    0                                          -                      1                                                        ⁡                                      (                                                                                            ϕ                          _                                                                          n                          ,                          m                                                                    ·                                                                        r                          _                                                                          tx                          ,                          s                                                                                      )                                                              )                                                                      ⁢                  ×                      exp            ⁡                          (                              j                ⁢                                                                  ⁢                2                ⁢                                  πυ                                      n                    ,                    m                                                  ⁢                t                            )                                ⁢                      δ            ⁡                          (                              τ                -                                  τ                                      n                    ,                    m                                                              )                                          where:
Frx,u,V and Frx,u,H: antenna element u field patterns for vertical and horizontal polarizations respectively
αn,mVV and αn,m,VH: complex gains of vertical-to-vertical and horizontal-to-vertical polarizations of ray n,m respectively
λ0: wave length of the carrier frequency
ϕn,m: angle of departure (AoD) unit vector
φn,m: angle of arrival (AoA) unit vector
rtx,s and rrx,u: location vectors of element s and u respectively
vn,m: Doppler frequency component of ray n,m.
This equation is typically implemented in computer models and channel emulation hardware. Each “link” defines a path between a base antenna and a mobile antenna. Each path m is made up of N sub-paths, where “n” is a sub-path index, so n, m denotes a sub-path component n of a path m in a channel of M paths.
However, as described herein, the use of a standard model at the channel emulation hardware does not allow proper control of the power levels at a device-under-test in a radiated dual polarized configuration.
An opportunity arises to provide a method of generating and transmitting a test signal for an OTA test of a device-under-test that is in simulated motion to allow proper control of the power levels.